A gas turbine generally includes a compressor, a combustor, and a turbine portion as main components; the compressor is coupled to a turbine with a rotating shaft; and the combustor is disposed between the compressor and the turbine portion.
In the above-described gas turbine, air, which is working fluid, is taken into the compressor, which is rotationally driven by the rotating shaft, to be compressed therein, and the compressed air is introduced into the combustor. Fuel is mixed with the compressed gas in the combustor, and high-temperature, high-pressure combustion gas is generated by combustion of the mixed air. The combustion gas is expelled to the turbine portion from the combustor to rotationally drive the turbine portion.
Specifically, the high-temperature working fluid expelled from the combustor, which includes the combustion gas, passes through between first-stage turbine stator vanes in the turbine portion and subsequently flows to first-stage turbine rotor blades. At the first-stage turbine rotor blades, part of the energy possessed by the working fluid is converted to rotational energy and is transmitted to the rotating shaft as a rotational driving force.
Normally, a rear end of a tail pipe of the combustor and leading edges of the first-stage turbine stator vanes positioned most upstream of the turbine portion are disposed with gaps therebetween. Accordingly, there is a problem in that part of the high-temperature working fluid that flows toward the turbine portion from the combustor flows into the gaps between the rear end of the tail pipe and the leading edges of the first-stage turbine stator vanes, and a loss occurs caused by this flow.
In addition, there is a problem in that the leading edges of the first-stage turbine stator vanes are heated by the high-temperature working fluid that has flowed into the gaps, and thus, a large amount of cooling fluid is required.
As a technique for solving the above-described problems, a method in which the first-stage turbine stator vanes are brought close to the combustor has been proposed (for example, see Patent Literature 1).
With the technique disclosed in Patent Literature 1, the leading edges of the first-stage turbine stator vanes are surrounded by the rear end of the combustor, and cooling fluid for cooling the first-stage turbine stator vanes is supplied from the tail pipe via slits formed at the leading edges. By doing so, the high-temperature working fluid does not collide with the leading edges of the first-stage turbine stator vanes, and the cooling fluid that was previously employed to cool the leading edges is not required.